Impingement Freezer

ABSTRACT

The present invention relates to an impingement freezer ( 1 ) comprising an outer housing ( 2 ) having side walls ( 3 ), ceiling ( 4 ) and floor ( 5 ), where the outer housing ( 2 ) comprises gas condition means ( 6 ), preferably for cooling gas and encloses a high-pressure chamber ( 7 ) formed by one or more ventilators ( 8 ) for circulating the gas, side panels ( 9 ) and a perforated plate ( 10 ), where the high-pressure chamber ( 7 ) is positioned so that the perforated plate ( 10 ) is facing a conveyor belt ( 11 ) for transporting products allowing the gas to be impinged through the perforated plate ( 10 ) onto the conveyor belt ( 11 ), which is arranged in a zone ( 19 ) between the perforated plate ( 10 ) and a plate member ( 12 ), and where the side walls ( 3 ) and the side panels ( 9 ) provides a return access channel ( 18 ) for the circulated gas, and the zone ( 19 ) is provided with at least one open side ( 20 ), which is open towards the return access channel ( 18 ).

FIELD OF THE INVENTION

The present invention relates to an impingement freezer comprising anouter housing having side walls, ceiling and floor, where the outerhousing comprises gas condition means, preferably for cooling gas andencloses a high-pressure chamber formed by one or more ventilators forcirculating the gas, and side panels and a perforated plate, where thehigh-pressure chamber is positioned so that the perforated plate isfacing a conveyor belt for transporting products allowing the gas to beimpinged through the perforated plate onto the conveyor belt, which isarranged in a zone between the perforated plate and a plate member, andwhere the side walls and the side panels provide a return access channelfor the circulated gas and that the zone is provided with at least oneopen side, which is open towards the return access channel.

BACKGROUND OF THE INVENTION

Impingement freezers are provided to quickly freeze products. By the useof impingement freezers products are placed on a conveyor belt runningeither below or above a perforated plate where through cooled gas isimpinged onto the products causing the products to freeze or cool down.

U.S. Pat. No. 4,584,849 describes a food freezing tunnel where theconveyor belt is positioned above a high pressure chamber and theproducts are impinged from below. The conveyor belt is arranged inside atunnel and the gas returns to a return access channel through anoverhead structure.

EP-B1-1143814 describes an apparatus for gas treatment of products wherethe conveyor belt is positioned below a high pressure chamber, and theproducts are impinged from above and below. The conveyor belt isarranged inside a tunnel, and the gas returns to a return access channelthrough end openings of channels in the bottom construction.

The drawback of the aforementioned apparatus is that the conveyor beltis arranged inside a tunnel, which provides high pressure resistancebecause the gas cannot easily escape the tunnel, and furthermore theimpingement of gas causes high pressure on the conveyor belt. Bothdecreases the efficiency of the impingement freezer, because theventilator must be dimensioned to overcome the pressure resistance andthe conveyor must be dimensioned to overcome the impingement pressure.As a result the impingement freezer as described has a large energyconsumption and low capacity.

One further drawback is that there is no imminent possibility ofcontrolling the impingement effect described. The only possibility is toregulate either the flow through the gas condition means or the effectof the gas condition means. However, this is not possible as the gascondition means typically works best at a certain gas flow or at acertain effect.

OBJECT OF THE INVENTION

It is therefore the object of the invention to provide an improvedimpingement freezer with a controllable and increased impingementeffect, and where the conveyor belt is easy to inspect, clean andreplace.

This object is obtained with an impingement freezer as described inclaim 1 and wherein an impingement freezer comprises an outer housinghaving side walls, ceiling and floor, where the outer housing comprisesgas condition means, preferably for cooling gas and encloses ahigh-pressure chamber formed by one or more ventilators for circulatingthe gas, and side panels and a perforated plate, where the high-pressurechamber is positioned so that the perforated plate is facing a conveyorbelt for trans-porting products allowing the gas to be impinged throughthe perforated plate onto the conveyor belt, which is arranged in a zonebetween the perforated plate and a plate member, and where the sidewalls and the side panels provide a return access channel for thecirculated gas and that the zone is provided with at least one openside, which is open towards the return access channel.

DESCRIPTION OF THE INVENTION

The impingement freezer comprises an outer housing having side walls,ceiling and floor, whereby a preferably gas tight room is provided,which is necessary for efficient circulation of the gas.

The floor can be a part of the floor in the room wherein the impingementfreezer is positioned or can be a separate floor, hence it is possibleto position the impingement freezer on e.g. a landing, a deck or onsupports or as a hanging unit.

The outer housing comprises gas condition means, preferably for coolinggas, which gas is used for freezing or cooling products. These gascondition means can be e.g. an evaporator, a heat exchanger,pizo-electrical elements, cooling fins or the like. The gas conditionmeans are arranged inside the outer housing so that the circulated gaspasses through it at least once whenever the circulated gas is impingedonto the product. Hence the gas condition means are arranged in or atthe end of the return access channel.

The gas can be air, nitrogen, carbon oxide or the like. The onlyparameter is that the product is able to cope with the gas and does notbecome contaminated by the gas.

The outer housing encloses a high-pressure chamber formed by one or moreventilators, side panels and a perforated plate. The ventilators cause apositive pressure in the high-pressure chamber thus causing the gas tobe circulated inside the impingement freezer.

The high-pressure chamber is positioned so that the perforated plate isfacing a conveyor belt for transporting products allowing the gas to beimpinged through the perforated plate onto the conveyor belt.

The conveyor belt is arranged in a zone between the perforated plate anda plate member and extends through the length of the outer housing, e.g.with a first end part outside the outer housing for placing products onthe conveyor belt and with a second end part outside the outer housingallowing the removal of the treated products. Preferably, the conveyorbelt is very open such that the gas may easily pass through the conveyorbelt.

The side walls of the outer housing and the side panels of thehigh-pressure chamber provide a return access channel for the circulatedgas on at least one side of the conveyor belt. The circulated gas isreturned into the high-pressure chamber after having passed the gascondition means.

To obtain an improved impingement freezer with a controllable andincreased impingement effect, the zone is provided with at least oneopen side, which is open towards the return access channel. Hence, theimpinged circulated gas is able to quickly exit the zone through thereturn access channel, and it is possible to circulate more gas aroundeach product on the conveyor belt thus increasing the impingementeffect.

One advantage is that the side, which is open towards the return accesschannel, reduces the back-pressure in the zone containing the conveyorbelt, thus it is possible for the ventilators to circulate the necessaryamount of gas with reduced energy consumption.

One further advantage is that a part of the circulated gas flows on theplate member in a direction perpendicular to the direction of theconveyor belt, hence helping to treat the products.

Therefore, a multidirectional gas flow is achieved, which may beadvantageous for certain shapes of products to be frozen.

According to a preferred embodiment of the present invention thehigh-pressure chamber is positioned above the conveyor belt, and theplate member is part of a bottom construction positioned below theconveyor belt. To ensure access of circulated gas for impingement frombelow, an access for the circulated gas is provided from thehigh-pressure chamber to the bottom construction.

This construction is preferred as the products typically are positionedon the upper side of the conveyor belt, and the main impingement occursfrom above through the perforated plate, where the circulated gas is indirect contact with the products, and the secondary impingement occursfrom below through the plate member, where the circulated gas bypassesthe conveyor belt to get in contact with the products.

To ensure optimal effect of the impingement freezer, the plate member isprovided with perforated channels and non-perforated channels, which arearranged preferably perpendicular to the travelling direction of theconveyor belt, and where the perforated channels have at least oneaccess for gas from the high-pressure chamber.

Thus it is possible to impinge products on the conveyor belt from aboveand below, hence securing faster and better freezing of the products onthe conveyor belt, and the capacity of the impingement freezer isincreased significantly.

The construction of the plate member with perforated channels andadjacent non-perforated channels allows the circulated gas to circulatethrough the perforated channels and impinge the products on the conveyerbelt and then to escape through the non-perforated channels to thereturn access channel.

The non-perforated channels ensure that a large part of the circulatedgas having impinged the products on the conveyor belt and which containsabsorbed heat, is led directly into the return access channel withoutdefrosting the products lying near the outer side of the conveyor belt.

To control the impingement effect, the plate member is replaceable, andthe non-perforated channels constitute between 20-70% of the platemember. Hence, it is possible to use a plate member, which is adapted tofit either the specific product on the conveyor belt or the level ofnecessary impingement of the product. The smaller the area of the platemember, which is constituted of non-perforated channels, the higherimpingement effect is obtained, and vice versa the larger the area ofthe plate member which is constituted of non-perforated channels, thelower impingement effect is obtained.

To secure uniform impingement effect throughout the width of the platemember, the perforated channels are formed with at least one inclinedbottom part. The inclined bottom part causes the channel to have aheight increasing from the point of gas access towards the return accesschannel. Hence, the back-pressure in the perforated channels decreasesthroughout the length of the perforated channels, and the circulatinggas has a uniform flow from the perforated channels of the plate memberinto the adjacently arranged non-perforated channels whatever positionalong the channels.

According to one embodiment of the present invention the impingementfreezer is built with multiple conveyor belts, where the high-pressurechamber extends above a number of the conveyer belts, and where theaccess for gas from the high-pressure chamber to the bottom constructionis arranged between the conveyer belts.

Typically the impingement freezer is built having two conveyor beltsarranged symmetrically inside the outer housing so that the access forgas from the high-pressure chamber to the bottom construction isarranged in the centerline of the outer housing and between the twoconveyer belts.

Hence, the circulated gas is led through the gas condition means intothe high-pressure chamber and causes impingement on each conveyor beltfrom above through the perforated plate and from below through the platemember of the bottom construction. Thus the gas on both sides of theimpingement freezer leaves the zone containing a conveyor belt throughthe channels in the plate member and the open side into the returnaccess channel.

To inspect or clean the high-pressure chamber or the perforated plate,the high-pressure chamber is provided with side panels, which can beopened wholly or partly.

To inspect or clean the perforated plate or the underlying conveyorbelt, the perforated plate is pivotally hinged. Hence, it is possible toget access to the conveyor belt from above.

To enter the outer housing for either inspection of the impingementfreezer or cleaning of the high-pressure chamber, the conveyor belt andthe bottom construction, the outer housing is provided with side panels,which can be opened wholly or partly.

As an alternative to openable side walls part of the side wall can beformed of a transparent material, hence it is possible to inspect theconveyor belt during the impingement process, without entering the outerhousing.

The impingement freezer according to the present invention can be usedfor freezing for example fish, meat, cookies, dough, vegetables or thelike. Alternatively, the impingement freezer is applicable for coolingliquid in e.g. bottles. One further alternative is to use theimpingement freezer to heat/bake products, however, to do so it isnecessary to use gas condition means like e.g. a heater, heating grills,heat exchanger or the like.

DESCRIPTION OF THE DRAWING

The invention is described in details in the following drawing, wherein

FIG. 1 shows a cross/side view of an impingement freezer according tothe present invention, and

FIG. 2 shows a cross/end view of an impingement freezer according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an impingement freezer 1 comprising an outer housing 2having side walls 3, ceiling 4 and floor 5.

The outer housing 2 comprises gas condition means 6 for cooling air andencloses a high-pressure chamber 7 formed by one or more ventilators 8for circulating the gas, side panels 9 and a perforated plate 10.

The high-pressure chamber 7 is positioned above the conveyor belt 11 sothat the perforated plate 10 is facing the conveyor belt 11 allowing thegas to be impinged through the perforated plate 10 onto the conveyorbelt 11, which is arranged in a zone (not shown) between the perforatedplate 10 and a plate member 12

The plate member 12 is part of a bottom construction 13 positioned belowthe conveyor belt 11 and the plate member 12 is provided with perforatedchannels 14 and non-perforated channels 15, which are arrangedpreferably perpendicular to the travelling direction of the conveyorbelt 11.

The conveyor belt 11 has a first end part 16 outside the outer housing 2for placing the products (not shown) on the conveyor belt 11 and asecond end part 17 outside the outer housing 2 allowing the removal ofthe treated products (not shown).

FIG. 2 shows the impingement freezer 1 comprising an outer housing 2having side walls 3, ceiling 4 and floor 5.

The outer housing 2 comprises gas condition means 6 for cooling air andencloses a high-pressure chamber 7 formed by ventilator 8 forcirculating the gas, side panels 9 and a perforated plate 10.

The side walls 3 and the side panels 9 provides a return access channel18 for the circulated gas.

The gas condition means 6 are arranged at the end of the return accesschannel 18, thus causing the circulated gas to pass through beforeentering the high pressure chamber 7.

The perforated plate 10 is pivotally hinged allowing access into thezone 19 from above.

The conveyor belt 11 is arranged in the zone 19 between the perforatedplate 10 and a plate member 12, and the zone 19 is provided with atleast one open side 20, which is open towards the return access channel18.

The perforated channels 14 are provided with one access 21 for gas fromthe high-pressure chamber 7, and the perforated channels 14 are formedwith inclined bottom part 22, hence causing uniform distribution of thecirculated gas.

1. Impingement freezer (1) comprising an outer housing (2) having sidewalls (3), ceiling (4) and floor (5), where the outer housing (2)comprises gas condition means (6), preferably for cooling gas, andencloses a high-pressure chamber (7) formed by one or more ventilators(8) for circulating the gas, side panels (9) and a perforated plate(10), where the high-pressure chamber (7) is positioned so that theperforated plate (10) is facing a conveyor belt (11) for transportingproducts allowing the gas to be impinged through the perforated plate(10) onto the conveyor belt (11), which is arranged in a zone (19)between the perforated plate (10) and a plate member (12), and where theside walls (3) and the side panels (9) provide a return access channel(18) for the circulated gas, and that the zone (19) is provided with atleast one open side (20), which is open towards the return accesschannel (18).
 2. Impingement freezer (1) according to claim 1, whereinthe high-pressure chamber (7) is positioned above the conveyor belt(11), and the plate member (12) is part of a bottom construction (13)positioned below the conveyor belt (11), and where there is access (21)for the gas from the high-pressure chamber (7) to the bottomconstruction (13).
 3. Impingement freezer (1) according to claim 1,wherein the plate member (12) is provided with perforated channels (14)and non-perforated channels (15), which are arranged preferablyperpendicular to the travelling direction of the conveyor belt (11), andwhere the perforated channels (14) have at least one access (21) for thegas from the high-pressure chamber (7).
 4. Impingement freezer (1)according to claim 1, wherein the plate member (12) is replaceable, andthe non-perforated channels (15) constitute between 20-70% of the platemember (129.
 5. Impingement freezer (1) according to claim 3, whereinthe perforated channels (14) are formed with at least one inclinedbottom part (22).
 6. Impingement freezer (1) according to claim 1,wherein the high-pressure chamber (7) extends above a number of theconveyer belts (11) and where the access (21) for the gas from thehigh-pressure chamber (7) to the bottom construction (13) is arrangedbetween the conveyer belts (11).
 7. Impingement freezer (1) according toclaim 1, wherein the high-pressure chamber (7) is provided with sidepanels, which can be opened wholly or partly (9).
 8. Impingement freezer(1) according to claim 1, wherein the perforated plate (10) is pivotallyhinged.
 9. Impingement freezer (1) according to claim 1, wherein theouter housing (2) is provided with side walls (3), which can be openedwholly or partly.